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SplPriorityQueue performance improvements #6859

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Merged
merged 4 commits into from
Apr 12, 2021
Merged

SplPriorityQueue performance improvements #6859

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a00f9b4
SplPriorityQueue - use specialized comparator when possible
kaja47 Apr 12, 2021
a61fb46
SplPriorityQueue - specialize spl_heap_elem_copy
kaja47 Apr 12, 2021
acdb983
requested code-review changes
kaja47 Apr 12, 2021
514a62f
requested changes #2
kaja47 Apr 12, 2021
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41 changes: 40 additions & 1 deletion ext/spl/spl_heap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,15 @@ static zend_always_inline void *spl_heap_elem(spl_ptr_heap *heap, size_t i) {

static zend_always_inline void spl_heap_elem_copy(spl_ptr_heap *heap, void *to, void *from) {
assert(to != from);
memcpy(to, from, heap->elem_size);

/* Specialized for cases of heap and priority queue. With the size being
* constant known at compile time the compiler can fully inline calls to memcpy. */
if (heap->elem_size == sizeof(spl_pqueue_elem)) {
memcpy(to, from, sizeof(spl_pqueue_elem));
} else {
ZEND_ASSERT(heap->elem_size == sizeof(zval));
memcpy(to, from, sizeof(zval));
}
}

static void spl_ptr_heap_zval_dtor(void *elem) { /* {{{ */
Expand Down Expand Up @@ -237,6 +245,22 @@ static int spl_ptr_pqueue_elem_cmp(void *x, void *y, zval *object) { /* {{{ */
}
/* }}} */

/* Specialized comparator used when we are absolutely sure an instance of the
* not inherited SplPriorityQueue class contains only priorities as longs. This
* fact is tracked during insertion into the queue. */
static int spl_ptr_pqueue_elem_cmp_long(void *x, void *y, zval *object) {
zend_long a = Z_LVAL(((spl_pqueue_elem*) x)->priority);
zend_long b = Z_LVAL(((spl_pqueue_elem*) y)->priority);
return a>b ? 1 : (a<b ? -1 : 0);
}

/* same as spl_ptr_pqueue_elem_cmp_long */
static int spl_ptr_pqueue_elem_cmp_double(void *x, void *y, zval *object) {
double a = Z_DVAL(((spl_pqueue_elem*) x)->priority);
double b = Z_DVAL(((spl_pqueue_elem*) y)->priority);
return ZEND_NORMALIZE_BOOL(a - b);
}

static spl_ptr_heap *spl_ptr_heap_init(spl_ptr_heap_cmp_func cmp, spl_ptr_heap_ctor_func ctor, spl_ptr_heap_dtor_func dtor, size_t elem_size) /* {{{ */
{
spl_ptr_heap *heap = emalloc(sizeof(spl_ptr_heap));
Expand Down Expand Up @@ -653,6 +677,21 @@ PHP_METHOD(SplPriorityQueue, insert)
ZVAL_COPY(&elem.data, data);
ZVAL_COPY(&elem.priority, priority);

/* If we know this call came from non inherited SplPriorityQueue it's
* possible to do specialization on the type of the priority parameter. */
if (!intern->fptr_cmp) {
int type = Z_TYPE(elem.priority);
spl_ptr_heap_cmp_func new_cmp =
(type == IS_LONG) ? spl_ptr_pqueue_elem_cmp_long :
((type == IS_DOUBLE) ? spl_ptr_pqueue_elem_cmp_double : spl_ptr_pqueue_elem_cmp);

if (intern->heap->count == 0) { /* Specialize empty queue */
intern->heap->cmp = new_cmp;
} else if (new_cmp != intern->heap->cmp) { /* Despecialize on type conflict. */
intern->heap->cmp = spl_ptr_pqueue_elem_cmp;
}
}

spl_ptr_heap_insert(intern->heap, &elem, ZEND_THIS);

RETURN_TRUE;
Expand Down